Process for the refining of metals.



-metal, such as iron JOSEPH B. r.

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To all whom it may concern:

Bt it known that I. J osnrH'B. MURRAY, a citizen of the United Brooklyn, in the county of Kings and ,State of New York, have invented acertain new and useful Improvement in Processes'for the Refining of Metals, of which the following is a specification.

Theinvention is a process for the refining of metals. g

It is well known that when a body of or steel, is heated from atmospheric temperature to a welding temerature, the structure changes at a certain critical temperature, the grains becoming coarser and the mass harder and more brittle. If the metal, during the heating, is worked or subjected to pressure, then this result is in a measure counteracted. I have discovered that if after the welding heat has been attained, the metal be allowed to cool while the working or pressure is continned, the following results take place. If the pressure be discontinued before the metal has cooled down to the aforesaid critical temperature, the grains will again enlarge and will continue so to do progressively for a period representing the difference between the temperature at the moment of removing the pressure and so that the beneficial effect of the combined heating andworking IS in agreater or less degree neutralized. But if, on' the other hand, the working or pressure he not stopped and until after 'themetal in cooling has passe the critical temperature, then not only are the said beneficial effects retained, but the metal has even a finer grain, closer structure greater ductility than it possessed beforev treatment. In other words, the process of heating the metal to a welding temperature and continuin the working or pressure during both the eating and the cooling and until Specification 01. Letters Patent.

States, residing at critical temperature means said critical temperature,

then cooling the same, while Patented Feb. 25, 1919.

Application filed August 3,1913. Serial No. 24am.

passed during the cooling, refines the metal.

As the temperature of change ture of the metal during heating may range between certain limits and. is not confin to some precise thermometric to be understood that the term,critical temperature, as herein set forth, includes not only a single precise degree,

ees between said certain limits, and that, in the latter instance, cooling below the cooling below the lower lnmt.

Thus, to illustrate: The critical points in steel vary, as is well known, with the carbon contained therein. In low carbon steels, for example, containing 10% carbon, three thermo critical radiations will be detected from 850 to 700. In this case theterm critical point as used by me means the lower critical point noted, or 700 In non-ferros metals which have but one critical temperature, then, of course, that critical temperature is the one to which I herein refer, but in the alloys, where there may be more than one critical temperature, then the lower critical temperature is the one to which I herein refer.

I claim: Y I The method of refining metal, which consists in heating said metal to a welding tem- In testimony w p signature in presence of two witnesses.

JOSEPH B. MURRAY.

Witnesses Gnm'nuna '1. Poem,

MAY '1. MCGARRY.

after the critical temperature has been of the strucdegree, it is 

